1. Field of the Invention
This invention relates to seatbelt systems and more particularly to passive seatbelt systems which automatically fasten and unfasten the seatbelt on the passenger.
2. Prior Art
It is recognized that passenger restraining belts restrain and protect the passengers during vehicular emergencies and therefore, contribute to the safety of the vehicle. In spite of this fact, however, the percentage of passengers who wear passenger restraining belts is very low because of the difficulties is fastening the belt, a feeling of pressure when belt is worn, etc.
As a result, various types of passive seatbelt systems have been proposed which make it possible to automatically fasten the belt around the passenger after the passenger is seated himself in the vehicle. Among these systems, the type of passive seatbelt system which includes a guide rail installed on the roof side member of the vehicle so that it is oriented in the direction of the length of the vehicle and an outer end of a passenger restraining seatbelt is fastened to a truck whose movement is guided by the guide rail has been highly rated in terms of reliability. The truck is coupled with a driving means such as a motor so that the truck can be caused to move back and forth in the direction of the length of the vehicle. In this manner, the belt can be caused to approach or move away from the passenger seat. Accordingly, the belt can be automatically fastened around or moved from the passenger seated in the passenger seat.
In such passive seatbelt systems, however, it is necessary to install the truck, guide rail and driving means on the roof side member of the vehicle. As a result, these parts project into the passenger compartment of the vehicle and thereby reducing the amount of space in the passenger compartment. In addition, there is a danger that the passenger will collide with one of these parts during a vehicular emergency such as a collision. Furthermore, there is a danger that a passenger's hair will become tangled with one of these parts when the truck is in operation.